The present invention relates to an amplifier arrangement for broadband signal.
It is known to use receivers for broadband communication systems, such as for asynchronous or asymmetric data(digital) subscriber loop (ADSL), or for high velocity data subscriber loop (VDSL), etc. Some of the known receivers provide an adaptive mechanism for reducing echo, such mechanism being for example a tuneable balance impedance on the balance of a classical hybrid as disclosed in IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, Vol. 9 No. 6, Aug. 1991, WALTER Y. CHEN, JAMES L. DIXON, DAVID L. WARING, xe2x80x9cHigh Bit Rate Digital Subscriber Line Echo Cancellationxe2x80x9d. Said transformers are expensive and inflexible.
Another example is a straight-forward wheatstone-bridge hybrid where one of the impedances can be tuned, as disclosed in ISSCC99/Sessions 14/paper tp14.4, MICHAEL MOYAL, MARTIN GROEPL, THOMAS BLON, xe2x80x9cA 25 kft 768 kb/s CMOS Transceiver for Multiple Bit-Rate DSLxe2x80x9d.
In the current art adaptive echo-cancelling is never combined with active back termination (EP-A-0.901.221). This reduces the power efficiency. Moreover the xe2x80x9cmatching pathxe2x80x9d in the wheatstone-bridge implementation is noisy when high impedant or power consuming when low impedant.
The amplifier arrangement of the invention is an arrangement enabling an efficient reduction of the noise without transformers. Other advantages of amplifier arrangement of the invention will be disclosed when describing a preferred embodiment of the arrangement of the invention.
The amplifier arrangement for transmitting and receiving a broadband signal of the invention comprises:
a resistive receive hybrid means adapted to pass a receive hybrid signal selected from the group consisting of combinations of a received signal and a transmitted signal, signals function of the received signal and of the transmitted signal, and combinations thereof,
a resistive transmit hybrid means that is adapted to pass a transmit hybrid signal corresponding substantially only the transmitted signal or a portion thereof or a function thereof,
a tuneable gain means adapted for converting the transmit hybrid signal into a gained transmit hybrid signal corresponding substantially to the reverse of or substantially equal to a portion of the receive hybrid signal corresponding to or function of the transmitted signal passing through the receive hybrid means, and/or for converting the receive hybrid signal into a gained received hybrid signal, the portion of which is function of the transmitted signal corresponding to the reverse of or being substantially equal to the transmit hybrid signal or to a function thereof,
signal treatment means adapted to add or subtract the gained transmit hybrid signal to and/or from a signal selected from the group consisting of the receive hybrid signal, a gained receive hybrid signal and/or a function thereof, and/or to add or subtract the gained receive hybrid signal to and/or from a signal selected from the group consisting of the transmit hybrid signal, a gained transmit hybrid signal and/or a function thereof, whereby said treatment is adapted for generating a signal which is substantially independent of the transmitted signal or a function thereof.
Advantageously, the tuneable gain means is adapted for converting the transmit hybrid signal into a gained transmit hybrid signal corresponding substantially to the reverse of or substantially equal to a portion of the receive hybrid signal corresponding to or function of the transmitted signal passing through the receive hybrid means, while the signal treatment means is adapted to add or subtract the gained transmit hybrid signal to and/or from the receive hybrid signal, whereby said treatment is adapted for generating a signal which is substantially independent of the transmitted signal or a function thereof.
Preferably, the resistive transmit hybrid means is adapted to tune said gain so that the gained transmit hybrid signal is substantially reverse to the portion of the transmitted signal passing through the receive hybrid means. In said case, the signal treatment means is advantageously adapted for adding the signal passed by the receive hybrid means and the gained transmit hybrid signal of said transmit hybrid means together. Preferably, the signal treatment means is then a differential inverter amplifier.
According to a detail of an advantageous embodiment, the resistive receive hybrid means comprises four resistors adapted for receiving a first signal function and a second signal function, each signal function comprising a linear combination of a receive signal and a transmit signal, said resistors being adapted for transferring a receive hybrid signal which is function of the difference between the first signal function and the second signal function.
According to still another detail of an advantageous embodiment, the resistive transmit hybrid means comprises four tuneable resistors adapted for receiving a first signal function and a second signal function, each signal function comprising a linear combination of a receive signal and a transmit signal, said resistors being adapted for transferring a transmit hybrid signal function of the difference between a linear combination of the first signal and a linear combination of the second function, whereby one of said linear combinations or said combinations are adapted so that said difference in not function of the receive signal.
The amplifier arrangement of the invention comprises advantageously an automatic gain control means and/or a line driver means for synthesising at least two combinations comprising each a linear combination of a receive signal and a transmit signal.
The invention relates also to the use of an amplifier arrangement of the invention in a broadband communication system, such as ASDL, VSDL, etc.